Flotation of sulfide ores using dithiocarbamates

ABSTRACT

A process of concentrating ores by flotation which comprises subjecting a sulfide ore in the form of a pulp to a flotation process in the presence of an effective quantity of a flotation collector comprising a compound corresponding to the formula   WHEREIN R and R2 are hydrocarbyl groups and R1 represents an alkylene or heteroalkylene group. These indicated compounds provide enhanced recovery of and/or selectivity for sulfide minerals of Cu, Zn, Mo, Co, Ni, Pb and As. The compounds are also useful as fungicides and herbicides.

United States Patent. [19] Harris et al.

[111 r 3,853,751 i 51 Dec. 10, 1974 FLOTATION OF SULFIDE ORES. USING DITHIOCARBAMATES [75] Inventors: Guy H. Harris, Concord; David J.

Collins, Walnut Creek, both of I Calif.

[7 3] Assignee: The Dow Chemical Company,

Midland, Mich.

' [22] Filed: Feb. 8, 1972 [21] Appl. No.: 224,616

52 us. Cl. 209/166 [51] Int. CL; 803d 1/02 [58] Field of Search 209/166, 167

[56] References Cited UNITED STATES PATENTS 2,375,083 5/1945- Cooper 260/455 A 3,424,730 l/l969 Lee t 260/455 A.X

3,464,551 9/1969 Falvey 209/l66 3,590,996 7/197] Harris 209/166 3,590,997 7/l97l Harris et al. 209/166 Primary ExaminerRobert Halper Attorney, Agent, or Firm J. Roger Lochhead 57 ABSTRACT A process of concentrating ores by flotation which comprises subjecting a sulfide ore in the formvof a pulp to a flotation process in the presence of an effective quantity of a flotation collector comprising a compound corresponding to the formula wherein R and R are hvdrocar byl groups and R represents an alkylene or heteroalkylene group. These indica'ted compounds provide enhanced recovery of and/or selectivity for sulfide minerals of Cu,,Zn, Mo, C0,. Ni, Pb and As. The compounds are also useful as fungicides and herbicides.

10 Claims, No Drawings- FLOTATION OF SULFIDE ORES USING DITHIOCARBAMATES BACKGROUND The present invention relates to novel dithiocarbamate esters and their use as flotation agents in the separation of sulfide ores.

Flotation is a process of treating a mixture of finely divided mineral solids, e.g., a pulverulent ore, suspended in a liquid whereby a portion of such solids are separated from other finely divided mineral solids, e.g., clays and other like materials present in the ore, by introducing a gas (or providing a gas in situ) in the liquid to produce a frothy mass containing certain of the solids on the top of the liquid, and leaving suspended (unfrothed) other solid components of the ore. Flotation is based on the principle that introducing a gas into a liquid containing solid particles of different materials suspended therein causes adherence of some gas to certain suspended solids and not to others and makes the particles having the gas thus adhered thereto lighter than the liquid. Accordingly, they rise to the top of the liquid to form a froth.

Various flotation agents have been admixed with the suspension to improve the frothing process. Such added agents are classed according to the function to be performed: collectors, e.g., high carbon chain com pounds such as collectors for sulfide minerals including xanthates, thionocarbamates, and the like; frothers which impart the property of forming a stable froth, e.g., natural oils such as pine oil and eucalyptus oil, modifiers such as activators to induce flotation in the presence of a collector, e.g., copper sulfate; depressants, e.g., sodium cyanide, which tend to prevent a collector from functioning as such on a mineral which it is desired to retain in the liquid, and thereby discourage a substance from being carried up and forming a part of the froth; pH regulators to produce optimum metallurgical results, e.g., lime, soda ash and the like. U.S. Pat. No. 3,464,55l discloses using dialkyl dithioas flotation collectors; U.S. Pat. No. 3,590,996 describes flotation of sulfide ores using certain thionocarbamates.

It is of importance to bear in mind that additives of the above'type are selected for use according to the nature of the ore, the mineral sought to be recovered, and the other additaments which are to be used in combination therewith.

An understanding of the phenomena which makes flotation a particularly valuable industrial operation is not essential to the practice of the present invention.

These compounds can be employed as collection agents in a flotation process. With some of these compounds better recoveries are realized and with others, improved selectivity is achieved. Certain of these compounds produce improvement in both aspects with some of the preceding sulphides.

SUMMARY The present invention concerns novel compounds corresponding to the formula wherein R represents H, a hydrocarbyl group, or a heterohydrocarbyl group, wherein said groups can be substituted with up to two functional groups and contain from 1 to 10 carbon atoms; R represents an alkylene or heteroalkylene group having a heteroatom substituted in the carbon chain, and R represents a hydrocarbyl or heterohydrocarbyl group, except for aryl, wherein either of said groups can be substituted except in the alpha position with up to two functional groups. The novel compounds can be prepared by the reaction of an amino alcohol with a trithiocarbonate ester and reacting the resulting hydroxyalkyl dithiocarbamate product with an acyl halide. The novel compounds can be employed to improve the flotation process of sepa rating sulfide minerals from ores by employing an effective quantity of at least one of the novel compounds set forth herein in the flotation process. The novel compounds are also useful as fungicides and herbicides.

PREFERRED EMBODIMENTS The preferred compounds of the present invention correspond to the formula wherein R represents H, a hydrocarbyl group selected from the group consisting of alkyl (e.g., methyl, ethyl, propyl, butyLdecyl) or alkenyl (e.g., vinyl, allyl, propenyl) containing up to 10 carbon atoms, alkaryl (e.g., tolyl), aryl (e.g., phenyl), aralkyl (e.g., benzyl, phenethyl), cycloalkyl (e.g., cyclopropyl, cyclohexyl), cycloalkenyl (e.g., cyclohexenyl), aralkenyl (e.g., phenylvinyl, cinnamyl), or acylalky] (e.g., acetylmethyl) groups, wherein the acyclic carbon chain portions preferably contain up to three carbon atoms and the cyclic group contains from five to 10 carbon atoms and a heterohydrocarbyl radical selected from the group consisting of alkoxy (e.g., methoxy), alkenyloxy (e.g., allyloxy), alkoxy carbonyl (e.g., methoxycarbonyl), alkoxycarbonylalkyl, aryloxy (e.g., phenoxy), arylalkoxy, alkylthio (e.g., ethylthio), alkylthioalkyl and arylthio groups, wherein said heterohydrocarbyl groups can contain up to two identical or different functional groups preferably selected from the group consisting of halo, alkoxy, cyano, acetonyl, and lower dialkylamino groups; R, represents an alkylene (e.g., ethylene, butylene 1,4 or 1,2) or heteroalkylene group containing up to eight carbon atoms and wherein the heteroatom is substituted in the carbon chain and is preferably selected from the group consisting of O, S and wherein X is a hydrocarbyl group and not H; preferably X is a lower alkyl group containing up to five carbon atoms; and R represents a hydrocarbyl group selected from the'group' consisting of an alkyl (e.g., methyl, ethyl, propyl, oct'yl) or alkenyl (e.g., allyl. hexenyl) group, preferably containing up to eight carbon atoms, an aralkyl group'(e.g., benzyl, phenethyl, phenylpropyl), preferably containing from one to three carbon atoms, in the alkyl portion, and an cycloalkyl or cycloalkenyl group, preferably containing from three to eight carbon atoms, wherein said hydrocarbyl groups can be substituted, except in the alpha position, with up to two identical or different functional groups prefera l5 METHODS OF PREPARATION The novel compounds as defined herein can be prepared, for example, by reacting an amino alcohol with a trithiocarbonate ester to prepare a hydroxy dithiourethane and then acylating the HOR, moiety with an 'acyl halide, anhydride or ketene. The reactions can be represented as follows:

The novel compounds as defined herein have a special utility as flotation collectors and can be employed in standard flotation processes to concentrate nickel and molybdenum sulfides and other like minerals from sulfide ores in preference to iron sulphides. In a flotation process a pulp is first prepared by wet grinding a sulphide containing ore to a suitable size with or without a pH modifier. A suitable frothing agent is then added, e.g., pine oil, cresylic acid, polyalkoxyparaffin and the like. An effective quantity of a flotation collector compound as defined herein is then added, usually ranging from about 0.01 lbs. to about 0.25 lbs. per ton of pulp, and thepulp is usually agitated and aerated. Sulfide minerals, e.g., copper, nickel, zinc, molybdenum sulphides, and other like sulfide minerals collect as a froth which is readily over-flowed or skimmed off from the residual gangue and other nondesired materials and the metal values therein recovered.

The following examples will facilitate a more complete understanding of the present invention but they are not meant to limit the scope of the invention to the specific embodiments incorporated therein.

EXAMPLE 1 A compound within the scope of the present invention and having the formula was prepared in the following manner:

To l5.l gms. of methyl 2-hydroxyethyldithiocarbamate (0.l0 mole) and 8.7 gms. of pyridine (0. ll mole) was added I 1.2 gms. of acetic anhydride (0| 1 mole) while cooling the mixture by means of an ice bath. The reaction temperature was allowed to rise to about 60C and after the reaction had subsided l0 ml. of methanol was added to consume any unreacted anhydride. The product was taken up in ether, washed with water, dilute HCl, saturated sodium bicarbonate solution and dried over MgSO Removal of the solid and solvent left 15 grams of product, the structure of which was confirmed by infrared and NMR analyses.

&C H N Calc 37.28 5.74 7.25 Obs 37.5 5.6 7.3

cine-o Cnnxrlc S2CH;

EXAMPLE 2 A novel compound corresponding to the formula Calc. for C H NO S 71 C H N Calc. 43.1! 6.84 6.32 Obs. 43.8 6.7 6.4

EXAMPLE 3 A new compound within the scope of the invention defined herein and corresponding to the formula 0 S m cocHzcnhrv-cfls CHtCHm was prepared in the following manner:

To 9 gms. of isopropyl 2-hydroxyethyldithiocarbamate and 5.5 gms. of triethylamine in ether was added .6 7 gms. of benzoyl chloride. The next day the solid was TABLE l-Continued removed and the filtrate was washed with water, satu- Compound rated aqueous sodium bicarbonate and then dried over empirical Acymlng MgSO powder. Removal of the solid and solvent left cm ms, CH3 p O I a syrup that became crystalline on standing. The melt- 5 I ing point was 1024C. CIHHNNOQSZ C2H4OC2H 0 i orrmclit J-lo o nNoa z .C2H4 iPr O Calc. for C l-l No s Q C2H'5O (Ig C1 C H N v nNozsz 01 13 iPr. o Calc. 55.29 6.04 4.94 7HCH2 (0H3(i)0 Obs. 55.9 6.2 5.0 CmHnNOaS: CH3

l5 (l' HCH2 C2H5O (P-C1 C1a 11N'OzSz C2H4 iPr 0 7 i-o1 C O C2HNHC S 2m cnHnNozsz 01Hu C1H5 0 (.9:: EXAMPLE 4 In a like manner to Example 3, the corresponding CmHnNoas OC C1 crotonyl compound was prepared from 9.2 grams of 3 isopropyl 2-hydroxyethyldithiocarbamate, 5.5 grns. of M triethylamine and 5.2 grams of crotonyl chloride.

I A150, HOC2H4N-C2H4NHCSZC3H7 CH2=C=O (gas) Other species of compounds within the scope of the CH present Invention can be prepared according to the 7 3 procedures set forth in Examples 1-4. The starting ma- CHECOTOCZHNTWHNHCSPCQHY- terials consistof a compound corresponding to the fortrans 2-butylene oxide mula r C C 3-0 1308 -.)R-CCCNHz is an example where S is the hetero II Suitable ati' latin nts h h r 8 R2 y arby gymupgxecgleldmw erem t e source 0 R equals a substituted and an'acylatmg agent which provides the 40 (D I ll (2) 3-cyanophenyl acetyl chloride: NC

moiety of the novel compounds. Various combinations CT C1 of R R and the acylatmg agent are set forth tn the fol- (3) cyanoacetyl chloride: 0 lowing Table 1, together Wltl'l the empirical formulas of Y NC C lg C1 the products which are formed.

TABLE 1 -The collectorsof Examples 2-3 were tested on a cop- Compound per sulfide ore from the Southwestern United States.

empirical R1 R2 Acylalmg agent The ore sample was ground for 4 minutes at 62.5 per- CsHisNOzSz CHzCH f cent solids with 1.0 lbs/ton of lime and 0.016 lbs/ton omc- 20 of collector. The pulp was conditioned for l minute CHHNNOzS2 CH3 a with 0.136 lbs/ton of a standard commercial frother.

The pulp was then floated for 5 minutes and the concentrate taili OHHNOi z c2115 C1H5 0 assayfid for Copper y 1| num. The results obtained are set forth In the following CH;--CH- CII3C ,0

Table 11.

' TABLE II Percent Copper Iron Molybdenum Content Content Content in con- Recovery in con- Recovery in con- Recovery Collector used centrate from ore centrete from ore centrete from ore Example'2 16.8 56.1 I 17.4 19.3 0. 46 76.3

Example 3 18. 7 56. 3 18. 2 16. 9 I 0. 52 75. 3

The collector of Example 2 was also tested on a nickel sulfide ore from Canada, a copper ore from North Central U.S.A. and a molybdenum ore from South Western U.S.A.

For the nickel ore, the sample was ground for minutes at 60.5 percent solids with 0.4 lbs/ton of lime and 0.09 lbs/ton of collector. The pulp was conditioned for one minute with 0.064 lbs/ton of a standard commercial frother. The pulp was then floated for 5 minutes and the concentrate tailings assayed for copper, iron and nickel.

The copper ore from North Central U.S.A. was treated in the following manner: Samples of ore were ground for 5 min. at a pulp density of 62.5 percent solids with 0.8 lbs/ton of lime and 0.128 lbs/ton of collector. The pulp was then transferred to a commercial laboratory flotation cell and conditioned for l min.

- with 0.094 lbs/ton of a standard frother. A concentrate was then removed in 5 mins. of flotation at a pH of 9.7. The concentrate and tailings were filtered, dried and assayed; results are presented below.

The molybdenum ore from South Western U.S.A. was tested in the following manner: Samples of ore were ground for 4 mins. at a pulp density of 62.5 percent solids with 0.4 lbs/ton of lime and 0.048 lbs/ton of collector. The pulp was then transferred to a commercial laboratory flotation cell and conditioned for l min. with 0.078 lbs/ton of a standard 'frother. A concentrate was then removed in 5 mins. of flotation at a and alkenylchloroformates such as and the like.

Other novel compounds of the invention may be prepared in a manner similar to that described in the foregoing examples. For example, a compound corresponding to the formula pH of 9.7. The concentrate and tailings were filtered, 3() dried and assayed; results are presented below: Table II! summarizes the data. (CHalta -COCUz-CH:NH-CSCH(CH3)2 TABLE MI Copper Iron Molybdenum Nickel Content Content. Content Content in con- Recovery in con- Recovery in eon- Recovery in eon Recovery Ore centrate from ore centrate from ore centrate from ore centrate from ore Ni ore 3. 4 88. 2 22. 2 26. O 3. 4 56. 2 Cu ore 15. 9 30. 7 4. 6 1.? Mo ore 13. 2 11. 2 12. 2 79, 9

For comparison, the O-ester or thiono analog of the Ex. 2 compound, i.e.,

o as i It can be prepared by Another compound corresponding to the formula can is prepared by the reactions:

Other compounds within the scope of the present invention may be prepared by a method as defined herein by choosing various starting materials.

What is claimed is: v

l. A process of concentrating sulfide ores by flotation, which comprises subjecting a sulfide ore of copper, nickel or molybdenum, in the form ofa pulp, to a flotation process in the presence of a flotation collector for said sulfides comprising a compound corresponding to the formula wherein R represents a member selected from the group consisting of H, a hydrocarbyl or a heterohydrocarbyl group; R represents a member selected from the group consisting of an alkylene or heteroalkylene group having the hetero atom substituted in the carbon chain and R represents a hydrocarbyl radical other than an aryl group.

2. The process as defined in claim 1 wherein R represents a member selected from the group consisting of a hydrocarbyl or heterohydrocarbyl radical containing up to two functional groups substituted thereon, and R represents a hydrocarbyl radical, other than an aryl group having up to two functional groups substituted thereon, other-than in the alpha position of said hydrocarbyl.

3. The process as defined in claim 1 wherein R represents H, a hydrocarbyl radical selected from the group consisting of alkyl or alkenyl containing up to carbon atoms, aryl, alkaryl; aralkyl, cycloalkyl, cycloalkenyl, aralkenyl or acylalkyl groups wherein the acyclic carbon chain portion contains up to three carbon atoms and the cyclic group contains from five to 10 carbon atoms, a heterohydrocarbyl selected from the group consisting of alkoxy, alkenyloxy, alkoxy carbonyl, alkoxycarbonylalkyl, aryloxy, alkylthio or arylthio groups; R represents a member selected from the group consisting of an alkylene or heteroalkylene group containing up to eight carbon atoms wherein the hetero atom in the heteroalkylene group is selected from the group consisting of O, S, and

wherein X is a hydrocarbyl radical and R represents a hydrocarbyl radical selected from the group consisting of an alkyl or alkenyl group, containing up to eight carbon atoms, an aralkyl, containing from one to three carbon atoms in the alkyl portion, and cycloalkyl or cycloalkenyl group, containing from three to eight carbon atoms, wherein R, R and R are further characterized in that the total number of carbon atoms in said groups range from about four to about 25.

4. The process as defined in claim 3 wherein R and R contain up to two functional groups other than in the alpha position of R selected from the group consis'ting of halo, alkoxy, cyano, acetyl or lower dialkylammo group.

5. The process as defined in claim 3 wherein X is a lower alkyl group containing up to five carbon atoms.

6. The process as defined in claim 1 wherein from about 0.01 to about 0.25 pound of compound per ton of sulfide ore pulp is employed.

7. The process defined in claim 1 wherein said compound consists of 8. The process as defined in claim 1 wherein said compound consists of 10. The process as defined in claim 1 wherein the sulfide ore is nickel sulfide ore or molybdenum sulfide Ol'. 

1. A PROCESS OF CONCENTRATING SULFIDE ORES BY FLOTATION, WHICH COMPRISES SUBJECTING A SULFIDE ORE OF COPPER, NICKEL OR MOLYBDENUM, IN THE FORM OF A PULP, TO A FLOTATION PROCESS IN THE PRESENCE OF A FLOTATION COLLECTOR FOR SAID SULFIDES COMPRISING A COMPOUND CORRESPONDING TO THE FORMULA R-COO-R1-NH-C(=S)-S-R2 WHEREIN R REPRESENTS A MEMBER SELECTED FROM THE ROUP CONSISTING OF H, A HYDROCARBYL OR A HETEROHYDROCARBYL GROUP; R1 REPRESENTS A MEMBER SELECTED FROM THE GROUP CONSISTING OF AN ALKYLENE OR HETEROALKYLENE GROUP HAVING THE HETERO ATOM SUBSTITUTED IN THE CARBON CHAIN AND R2 REPRESENTS A HYDROCARBYL RADICAL OTHER THAN AN ARYL GROUP.
 2. The process as defined in claim 1 wherein R represents a member selected from the group consisting of a hydrocarbyl or heterohydrocarbyl radical containing up to two functional groups substituted thereon, and R2 represents a hydrocarbyl radical, other than an aryl group having up to two functional groups substituted thereon, other than in the alpha position of said hydrocarbyl.
 3. The process as defined in claim 1 wherein R represents H, a hydrocarbyl radical selected from the group consisting of alkyl or alkenyl containing up to 10 carbon atoms, aryl, alkaryl, aralkyl, cycloalkyl, cycloalkenyl, aralkenyl or acylalkyl groups wherein the acyclic carbon chain portion contains up to three carbon atoms and the cyclic group contains from five to 10 carbon atoms, a heterohydrocarbyl selected from the group consisting of alkoxy, alkenyloxy, alkoxy carbonyl, alkoxycarbonylalkyl, aryloxy, alkylthio or arylthio groups; R1 represents a member selected from the group consisting of an alkylene or heteroalkylene group containing up to eight carbon atoms wherein the hetero atom in the heteroalkylene group is selected from the group consisting of -O-, -S-, and
 4. The process as defined in claim 3 wherein R and R2 contain up to two functional groups other than in the alpha position of R2, selected from the group consisting of halo, alkoxy, cyano, acetyl or lower dialkylamino group.
 5. The process as defined in claim 3 wherein X is a lower alkyl group containing up to five carbon atoms.
 6. The process as defined in claim 1 wherein from about 0.01 to about 0.25 pound of compound per ton of sulfide ore pulp is employed.
 7. The process defined in claim 1 wherein said compound consists of
 8. The process as defined in claim 1 wherein said compound consists of
 9. The process as defined in claim 1 wherein said compound consists of
 10. The process as defined in claim 1 wherein the sulfide ore is nickel sulfide ore or molybdenum sulfide ore. 